Peer-to-peer communications in ami with source-tree routing

ABSTRACT

Methodologies are provided for establishing peer-to-peer communications between nodes in a tree structured network having plural nodes including a root node. A source node seeking to send a message to a destination node will first request a most advantageous available path from the source to the destination node, and then the root node (or possibly another node within the network that has additional storage resources) will provide a routing path to one or both of the source and destination nodes. Messages may then be sent between the source and destination nodes that may or may not include addressing information in the packet headers without having to request routing information again for additional messages between the same nodes.

FIELD OF THE SUBJECT MATTER

The presently disclosed subject matter relates to communications. Morespecifically, the presently disclosed subject matter relates topeer-to-peer routing in an advanced metering infrastructure (AMI).

BACKGROUND OF THE SUBJECT MATTER

Generally, an Advanced Metering Infrastructure (AMI) may contain up tomillions of metering devices distributed over a large geographical area.Such devices are typically configured to exchange messages includingdata, for example, utility consumption data, with a cluster of serversincluding data metering collectors, and network management servers. AMIenvironments are generally organized around Autonomous Systems (AS)headed by cell relays (sometimes referred to as cell routers), whereeach AS is connected by way of a back-haul network to servers that maybe located at a utility home-office or other central location.

Those of ordinary skill in the AMI art will appreciate that the logicalinfrastructure interconnecting the metering devices or endpoints and thecell relays/routers is frequently based on a tree topology, on top of,for example, a wireless mesh network or a wired network, such as usingpower lines.

Typically, the nodes forming the AS can be classified into two broadclasses of devices or nodes, with respect to the resources available ateach respective device/node. Such broad classes include fullfunctionality nodes/devices and reduced functionality nodes/devices.Full functionality nodes are devices that typically have relativelylarge memory space and high processing power, while reducedfunctionality nodes correspond to devices that typically have relativelysmaller memory space and lower processing power.

One of the main challenges for routing in an AMI network with reducedfunctionality nodes is the implementation of an efficient routingscheme. The resource constraints of such nodes make the storing andmaintenance of large routing tables a practical impossibility.Eventually, such nodes often maintain a greatly reduced or “lite”routing table with routes toward a very few of their one-hop neighbors.Typically, such nodes only store information about their one-hopupstream neighbors, sometimes called their parents. In such context, itshould be appreciated by those of ordinary skill in the art that storingin such nodes more detailed routing information to reach neighbors thatmay be several-hops away is very challenging.

In frequent cases, the only node within an established tree that has aglobal view on the network may be what is referred to as the root of thetree. The root has enough resources to accommodate detailed routinginformation and maintain route/routing information to each node withinthe tree. As those of ordinary skill in the art will appreciate, pathcomputation towards each node can in straightforward fashion beimplemented using known techniques once the root has detailed knowledgeon topology and available links.

The routing schemes in such tree topologies are typically organizedaround two kinds of flows: upstream flows and downstream flows. Upstreampackets flow from tree leaves up to the root of the tree (multipoint topoint), while downstream packets flow from the tree root towards theleaves (point to multipoint). Upstream messages are always destined forthe root of the tree, while downstream messages can be destined to anyof the tree nodes.

Upstream routing is simple in that each node (even reduced functionalitynodes that have at least one entry in their routing table for upstreamneighbors that receives a message destined for the root simply forwardsit upstream to its one-hop neighbor (parent). Downstream routing uses asource routing approach. That is, the root of the tree inserts theexplicit route information, including all the addresses of theintermediate nodes/hops between the source and the destination of themessage, into the header of a downstream packet. Here, each intermediatenode that receives a packet inspects the routing header of the packet(which is a list with the complete path), processes and consumes/removesthe header containing its address, and further forwards the packet tothe next-hop on the list.

As is understood by those of ordinary skill in the AMI art, intermediatenodes do not need to store tables listing their downstream neighborsbecause wireless networks are a broadcasting domain so that a unicastmessage transmitted by a node is inherently heard by all of itsneighbors. Such person of ordinary skill in the art will also appreciatethat source routing is not an issue for such hardware-constrained nodes,and that end-to-end reliability can be achieved by deploying one-hopretransmission mechanisms, at link-layer, as well as end-to-endretransmission mechanisms at higher layers.

As may be seen, within an AMI environment communications betweenendpoints (that is, for example, metrology devices) and a tree root (ormore generally a central facility that may be generally designed tocollect data from the various endpoints) is a fairly straightforwardprocess. More recently, however, there has been expressed increasinginterest in providing communications capabilities between peer devicesfor providing such features as demand response and automationcommunications. It would be advantageous, therefore, to provideefficient peer-to-peer communication capabilities between the nodes ofthe tree, when the source and destination of such communications arepresumptively not the root of the tree. Using only previously knownrouting mechanisms, the tree nodes cannot set-up peer-to-peercommunications directly. That is, peer-to-peer communications betweennodes that are not roots must per the current state of the art be routednonetheless via the root of the tree. As such, it would be advantageousto provide improved routing capabilities that would provide peer-to-peerrouting optimizations for advanced metering infrastructure applicationsin an open operational framework.

While various aspects and alternative embodiments may be known in thefield of AMI routing, no one design has emerged that generallyencompasses the above-referenced characteristics and other desirablefeatures associated with peer-to-peer communication technology as hereinpresented.

SUMMARY OF THE SUBJECT MATTER

In view of the recognized features encountered in the prior art andaddressed by the presently disclosed subject matter, improvedmethodology for providing source node initiated communications fornetworked devices including automated meter reading (AMR) devicescommunicating over advanced metering infrastructure (AMI) and other widearea network (WAN) environments is provided.

The presently disclosed subject matter relates, for example, to a methodfor establishing peer-to-peer communications in a tree structurednetwork having a plurality of nodes, and in some embodiments including aroot node. The method includes sending a message from a source noderequesting information from the root node for path routing from suchsource node to a destination node. The most advantageous path betweenthe source node and the destination node is determined by the root, andsuch determined path information is then sent to the source node. Thesource node then transmits a message to the destination node using thepath information.

In some embodiments, the method further may include sending a messagefrom the destination node to the root requesting reverse routing pathrouting to the source node and sending reverse routing path informationto the destination node. In selected embodiments, the reverse pathinformation may be automatically sent to the destination node by theroot so that the destination node may respond to a message from thesource node without first requesting path information. In otherembodiments, present methodology may provide for configuring at leastone of the source and destination nodes to cache the path information sothat repeating the path request may be avoided.

In some embodiments making use of a root node, the root node may beconfigured to determine the most advantageous path and to send the pathinformation to the source node. In other embodiments, at least one fullfunctionality node—other than the root—may be provided among theplurality of nodes and configured to store routes within the tree. Insuch exemplary embodiments, the at least one full functionality node maydetermine the most advantageous path and send the path information tothe source node.

In selected embodiments, the method may provide for configuring nodes ina communications path from a source node to a destination node to storethe address of the next-hop from the packet header of a previouscommunication. In such exemplary embodiments, subsequent packets fromthe same source to the same destination may be sent without addingsource routing information into the header of the packet.

In other exemplary embodiments of the presently disclosed subjectmatter, the method may provide for configuring nodes in the path betweenthe source node and the destination node to forward message packetheaders unchanged so that the destination node may learn the reverseroot path to the source node. In selected alternative embodiments of thepresently disclosed subject matter, the method may provide forconfiguring the destination node to process heard packets destined toitself for errors and to announce a new peer-to-peer route to the sourcenode.

The presently disclosed subject matter also relates to methodology forestablishing peer-to-peer communications in an advanced meteringinfrastructure. In accordance with such exemplary methods, a pluralityof nodes (in some instances including a root node) are provided andconfigured as a tree structured network. In such exemplary methods, afirst node of the plurality of nodes is configured to initiatepeer-to-peer communications with a second of the plurality of nodes byrequesting a route to the second of the plurality of nodes. The mostadvantageous path/route between the first node and the second node isdetermined and a message packet is transmitted from the first node tothe second node. In selected of such exemplary methods, the messagepacket may include a header including the path information. In selectedof such embodiments, the root node may be configured to determine themost advantageous path between the first node and the second node and totransmit the path information to the first node.

In selected alternative embodiments of such exemplary methods, at leastone full functionality node is provided within the plurality of nodes.In such embodiments, at least one full functionality node is configuredto respond to the first node's request for path routing. In yet furtherembodiments of the presently disclosed subject matter, at least oneselected node of the plurality of nodes are provided as wireless nodes.In such exemplary embodiments, the wireless nodes may be configured tolisten for messages not necessarily addressed to themselves, to evaluatereceived messages for errors, to inspect routing header, and to announceeventual path optimizations/changes to the source of the messages if a“shorter” path is available.

In other present exemplary implementations of the foregoing, determiningwhat constitutes a most advantageous path between an exemplary sourcenode and an exemplary destination node may include using predeterminedrouting metrics so that predefined routing objectives are achieved.

Additional objects and advantages of the presently disclosed subjectmatter are set forth in, or will be apparent to, those of ordinary skillin the art from the detailed description herein. Also, it should befurther appreciated that modifications and variations to thespecifically illustrated, referred and discussed features, elements, andsteps hereof may be practiced in various embodiments and uses of thesubject matter without departing from the spirit and scope of thesubject matter. Variations may include, but are not limited to,substitution of equivalent means, features, or steps for thoseillustrated, referenced, or discussed, and the functional, operational,or positional reversal of various parts, features, steps, or the like.

Still further, it is to be understood that different embodiments, aswell as different presently preferred embodiments, of the presentlydisclosed subject matter may include various combinations orconfigurations of presently disclosed features, steps, or elements, ortheir equivalents (including combinations of features, parts, or stepsor configurations thereof not expressly shown in the figures or statedin the detailed description of such figures). Additional embodiments ofthe presently disclosed subject matter, not necessarily expressed in thesummarized section, may include and incorporate various combinations ofaspects of features, components, or steps referenced in the summarizedobjects above, and/or other features, components, or steps as otherwisediscussed in this application.

Yet further, it is to be understood that the presently disclosed subjectmatter equally encompasses corresponding devices and apparatus forpracticing the present exemplary methodologies, and/or for operating inaccordance with such exemplary methodologies. Those of ordinary skill inthe art will better appreciate the features and aspects of suchembodiments, and others, upon review of the remainder of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the presently disclosed subjectmatter, including the best mode thereof, directed to one of ordinaryskill in the art, is set forth in the specification, which makesreference to the appended figures, in which:

FIG. 1 diagrammatically illustrates the present inability to provide forpeer-to-peer communications between peer nodes without forwarding thetraffic via the root node;

FIG. 2 diagrammatically illustrates a source node initiated peer-to-peercommunication between peer nodes in accordance with an exemplaryembodiment of the presently disclosed subject matter;

FIG. 3 is a block diagram illustrating an exemplary message sequencechart (MSC) of a peer-to-peer route request in accordance with a firstembodiment of the presently disclosed subject matter; and

FIG. 4 is a block diagram illustrating an exemplary message sequencechart (MSC) of a route request in accordance with a further embodimentof the presently disclosed subject matter.

Repeat use of reference characters throughout the present specificationand appended drawings is intended to represent same or analogousfeatures, elements, or steps of the presently disclosed subject matter.

DETAILED DESCRIPTION OF THE SUBJECT MATTER

As discussed in the Summary of the Subject Matter section, the presentlydisclosed subject matter is particularly concerned with methodology forproviding a source node initiated peer-to-peer routing scheme in treeorganized networks including such as in an advanced meteringinfrastructure (AMI).

With initial reference to FIG. 1, the basic concept for the presentlydisclosed subject matter recognizes that when an application layer of,for example, node 102 in, for example, an AMI system tree 100 has amessage to send to an address other than the address of the root node104, node 102 must ordinarily route a message to root node 104requesting the explicit path towards destination node 106. When rootnode 104 receives such message, it responds back to node 102 with thepresently most advantageous known path towards node 106, which, ofcourse, includes a path via root node 104 (upstream path 112 thendownstream path 114) as opposed to a more direct route such as route 116which, in the prior configuration of FIG. 1, is not possible.

The main drawbacks associated with such approach include increasedlatency, increased probability of collisions, and unnecessary loading ofsome nodes and branches in the tree. Latency in delivering peer-to-peermessages is increasing since the path used to deliver the peer-to-peermessages is sub-optimal. This is due to the fact that a message does nottake the “shortest” available path. Generally, the shortest path shouldpreferably be interpreted as the optimal path between the source and thedestination of the message, as a function of the objective ofoptimization functionality (i.e., high probability of successfultransmission). In the instance illustrated in FIG. 1, a packetordinarily travels upstream from node 102 via path 112 to root node 104of the tree 100 and then downstream via path 114 to its finaldestination, exemplarily, node 106.

Peer-to-peer communication via the root node 104 of the tree 100 issubject to an increasing probability of collisions and thus increasinglysubject to end-to-end delay. For example, consider that the probabilityof successful transmission of a packet between two adjacent nodes is p,and the probability of collision is q=1−p. For a communication where thesource and the destination are 1-hop away, e.g., nodes 102 to 122 inFIG. 1, the probability of success is p(1−q)̂2. For a communication wherethe source and destination are separated by N intermediate nodes, theprobability of success is p(1−q)̂(N+1). It should be clear then thatdecreasing the number N of intermediate hops increases the probabilityof successful transmission and thus decreases the end-to-end delay.

Another drawback of the messaging system represented by FIG. 1 is thatsome branches and nodes of the tree 100 are unnecessarily loaded. Forexample, the link between root node 104 and node 124, and thus root node104 itself, is unnecessarily loaded with additional upstream anddownstream traffic. In addition spatial re-use, when available, of thenetwork resources, i.e., frequencies, may be considerably reduced. Forexample, as illustrated in FIG. 1, communications between node 102 and106 can unnecessarily monopolize the resources between root node 104 andnode 124 and thus make root node 104 unavailable for receiving and/orsending messages from or to other neighbor nodes.

In accordance with presently disclosed technology, such drawbacks andothers are addressed by providing alternative paths for peer-to-peermessages. With reference now to FIG. 2, in one representation ofexemplary embodiment of presently disclosed technology, a source node,exemplarily node 202, sends an explicit path request message to rootnode 204 of the tree 200, by using an upstream message along path 212.Root node 204 has a complete view of the topology of tree 200 andmaintains explicit path information towards all the nodes. In suchmanner, root node 204 can easily compute the most advantageous knownpath between, for example, nodes 202 and 206 and further can send thepath information back to a requesting node, for example node 202.

In accordance with further aspects of the presently disclosed subjectmatter, a few full functionality nodes may be either uniformly orrandomly dispatched among the nodes within each Autonomous Systems (AS)as represented by trees 100, 200 of FIGS. 1 and 2. Such nodes, forexample nodes 234, 222, and 252, may be configured with enough resourcesto store detailed information on one-hop and/or several hops routeswithin each AS. In such instance, such nodes per the presently disclosedsubject matter act as router nodes and announce their presence withinthe Autonomous Systems (AS). In such case, each node can request apeer-to-peer communication path from the nearest router (fullfunctionality node) instead of from the root node.

A message sequence chart (MSC) of such exemplary present methodology isdepicted in FIG. 3. As illustrated, node 202 may send a route request toroot 204, or other full functionality node. Root 204, or other fullfunctionality node, then computes the most advantageous known pathbetween nodes 202 and 206 and responds with a route request reply givingthe address sequence which corresponds in this instance to the addressof node 222 followed by the address of node 224 followed by the addressof node 226.

If node 206 must respond to messages received from node 202, node 206per presently disclosed subject matter may send an identical routerequest message to root node 204, or other full functionality node, inorder to obtain the reverse route to node 202. Furthermore, either orboth of nodes 202 and 206 per presently disclosed subject matter may beconfigured to cache the path provided by root 204, or other fullfunctionality node, to avoid repeating the path request for each packetto be send to its peer.

In a further embodiment or aspect of the presently disclosed subjectmatter, the first peer-to-peer packet may maintain its routing headerstructure unchanged up to its destination. That is, intermediate nodesdo not remove their addresses from the packet header. By such technique,per presently disclosed subject matter, destination node 206 can readilydetermine the reverse route to node 202, assuming the intermediatepaths/links are bidirectional in the sense that they have similarcommunication quality in both directions.

In yet another exemplary embodiment of the presently disclosed subjectmatter, under an assumption that a peer-to-peer communication betweennodes is bidirectional, that is, in the sense that a message sent fromnode 202 to node 206 will generate a response from node 206 to node 202,root node 204, upon receiving a request for an explicit path betweennode 202 and node 206, may be configured, as it responds back to node202 as previously described, to automatically send the reverse path tonode 206. A message sequence chart (MSC) of such present exemplarymethodology is depicted in FIG. 4.

With reference to FIG. 4, when root node 204, or other fullfunctionality node, receives a route request from node 202, the nodegenerates two messages. A first of the messages corresponds to a RouteRequest Reply that is made to the source of the message, i.e. in thisinstance, node 202. The second of the messages corresponds to a RouteAnnouncement and is made to the node located at the end of thepeer-to-peer route, i.e., in this instance, destination node (node 206)for the subject peer-to-peer communication. As represented in presentexemplary FIG. 4, the address sequences sent to node 202 and node 206are mirror images of each other, representing the different directionsbetween the two nodes towards each other.

In a still further exemplary embodiment of the presently disclosedsubject matter, the peer-to-peer communication between nodes 202 and 206may be enhanced by an auto-learning mechanism. In such exemplaryembodiment, after node 202 sends a first peer-to-peer communicationpacket to node 206 each node along path 216 between nodes 202 and 206,such nodes (that is, nodes 222, 224, 226) learn from the packet headerthe address of the next-hop for reaching the destination node 206. As anexample, for the destination 206, the intermediate node 222 will storeas next-hop the address of node 224, node 224 will store as next-hop theaddress of node 226, and finally node 226 will store as next-hop theaddress of the node 206.

Node 202 may then send following packets to node 206 without addingexplicit route information into the header of the packet. When node 222,which is listening to the medium, receives a packet destined to node206, it will receive the packet, process it, and will simply forward itto the next-hop address 224. Then, node 224 will forward the packet tonode 226, and so on until the packet reaches its final destination 206.

In a further additional present exemplary embodiment, if the destinationnode 206 “hears” a peer-to-peer packet destined to itself from node 202,and routed as previously described, it will process the packetcompletely. If no error is detected, that is, no bits are corrupted due,for example, to interference, node 206 acknowledges back to node 202 theproper reception of the packet. That is, the node 206 announces to node202 that they can communicate directly and a shorter route may be set upfor the peer-to-peer communication between nodes 202 and 206, all inaccordance with the presently disclosed subject matter.

For example, in the instance that the nodes are a part of a wirelessmesh network, each node broadcasts its messages such that many paths maybe created among various nodes. As previously described, the mostadvantageous path from node 202 to node 206 had been along path 216 vianodes 222, 224, and 226. In the case, however, where destination node206 may have “heard” a packet destined to itself being broadcast fromnode 222 via direct path 218 and where no errors in the transmissionwere detected, the path from node 202 to 206 may be changed to theshorter route, in accordance with an aspect of the presently disclosedsubject matter.

In accordance with additional, optional aspects of the presentlydisclosed subject matter, in various exemplary implementations of theforegoing, determining what constitutes a most advantageous path betweenan exemplary source node and an exemplary destination node may includeusing predetermined routing metrics so that predefined routingobjectives are achieved. Generally speaking, routing protocols forwireless networks focus on finding the most advantageous path, and inthis instance eventually what would be the most advantageous alternativepaths which helps to ensure the required quality of service for a givenapplication. As understood by those of ordinary skill in the art withoutrequiring detailed explanation, quality of service in such context maybe expressed in terms of latency and reliability. For someimplementations, routing metrics for wired networks make use of hopcount and physical capacity to determine what constitutes a mostadvantageous path, which means the arrangements seek to achieve minimumhop count or maximum bandwidth. Wireless paths have significantlydifferent characteristics compared to wired links, such as low capacityand high packet error rate, leading to relatively poorer throughput.Accordingly, a routing algorithm for a wireless network preferablyselects most advantageous path in a given context by explicitly takingthe quality of the wireless links into account.

It will be understood by those of ordinary skill in the art that forvarious implementations of the presently disclosed subject matter,different routing metrics can be used to estimate characteristics of apath between source and destination. For example, some routing metricsmay be intended to capture the stability of a path, while others mayfocus on energy consumption, and still others may be more focused on theresulting bandwidth of a determined path. Further, other metrics may beused to estimate the quality of the wireless links, including thosewhich take into account the packet error rate on the link, such as ETX.As well known to those of ordinary skill in the art, the ETX metric of awireless link is the expected number of transmissions required tosuccessfully transmit and acknowledge a packet on a link. Those ofordinary skill in the art, within the broader context of the presentlydisclosed subject matter, may implement path calculation algorithms(details of which form no specific aspect of the presently disclosedsubject matter) which will use metrics in order to find the mostadvantageous path (or eventual alternative most advantageous paths) fora given context. Furthermore, it is to be understood that such metricsin some instances may be static, or they may dynamically change, such asa function of the estimated wireless link quality.

While the presently disclosed subject matter has been described indetail with respect to specific embodiments thereof, it will beappreciated that those skilled in the art, upon attaining anunderstanding of the foregoing, may readily produce alterations to,variations of, and equivalents to such embodiments. Accordingly, thescope of the present disclosure is by way of example rather than by wayof limitation, and the subject disclosure is not intended to precludeinclusion of such modifications, variations, and/or additions to thepresently disclosed subject matter as would be readily apparent to oneof ordinary skill in the art.

1. A method for establishing peer-to-peer communications in a treestructured network having a plurality of nodes including a root node,comprising: sending a message from a source node to one of a root nodeor a router node, either one of which has functionality capable ofstoring routes within the tree structured network, requesting pathrouting to a destination node; determining at the root node or routernode at least one of the shortest or most direct path between the sourcenode and the destination node; sending the determined path informationto the source node; and transmitting a message from the source node tothe destination node using the path information.
 2. A method as in claim1, further comprising: sending a message from the destination node tothe root node or router node requesting reverse routing path routing tothe source node; and sending reverse routing path information to thedestination node.
 3. A method as in claim 1, further comprising:automatically sending reverse path information to the destination node,whereby the destination node may respond to a message from the sourcenode without first requesting path information.
 4. A method as in claim1, further comprising: configuring at least one of the source anddestination nodes to cache the path information, whereby repeating thepath request may be avoided.
 5. A method as in claim 1, wherein the rootnode determines and sends the path information to the source node.
 6. Amethod as in claim 1, further comprising: storing routes within at leastone router node of the tree structured network, wherein the at least onerouter node determines and sends the path information to the sourcenode.
 7. A method as in claim 1, further comprising: storing the addressof the next-hop in nodes in a communications path from a source node toa destination node based on the packet header of a previouscommunication, whereby subsequent packets from the same source to thesame destination may be sent without adding route information into theheader of the packet.
 8. A method as in claim 1, further comprising:forwarding message packet headers unchanged through nodes in the pathbetween the source node and the destination node, whereby thedestination node determines the reverse root path to the source nodebased on the unchanged headers.
 9. A method as in claim 1, furthercomprising: processing packets heard by the destination node notnecessarily destined to such destination node; and announcing from thedestination node a new peer-to-peer route to the source node.
 10. Amethod as in claim 1, wherein selected of said plurality of nodescomprise data endpoints.
 11. A method as in claim 10, wherein selectedof said data endpoints are associated with metering devices in anadvanced metering infrastructure.
 12. A method as in claim 1, whereinsaid plurality of nodes comprises metering devices with associatedwireless communication devices.
 13. A method as in claim 12, whereinsaid metering devices are respectively associated with wirelesscommunication devices.
 14. A method as in claim 1, wherein determiningthe path between the source node and the destination node comprisesusing predetermined routing metrics so that predefined routingobjectives are achieved.
 15. A method for establishing peer-to-peercommunications in an advanced metering infrastructure, comprising:providing a plurality of nodes including a root node configured as atree structured network; initiating peer-to-peer communications from afirst node of the plurality of nodes with a second of the plurality ofnodes by requesting from the root node a path routing to the second ofthe plurality of nodes; determining at the root node at least one of theshortest or most direct path between the first node and the second node;and transmitting a message packet from the first node to the second nodeusing the determined path.
 16. A method as in claim 15, wherein themessage packet includes a header including the path information. 17.(canceled)
 18. A method as in claim 15, further comprising respondingfrom at least one full functionality node to the first node's requestfor path routing.
 19. A method as in claim 15, wherein: at leastselected of the plurality of nodes are wireless nodes; and said methodfurther comprises listening for messages at the wireless nodes notnecessarily addressed to themselves, evaluating received messages forerrors, and announcing path changes to a node sending them messages if ashorter path is available.
 20. A method as in claim 15, furthercomprising: caching at least a portion of the path information in nodesalong a path between the first node and the second node, wherebyrepeating the path request may be avoided.
 21. A method as in claim 15,wherein said plurality of nodes respectively comprise metering deviceswith associated wireless communications devices.
 22. A method forcommunications in an advanced metering infrastructure associated with aplurality of nodes at least selected of which are associated withmetering device endpoints configured as a tree structured networkutilizing wireless communications, comprising: initiating peer-to-peercommunications from a selected source node of the plurality of nodeswith a selected destination node of the plurality of nodes by requestingfrom a root node a path routing to such destination node using such treestructured network; determining at the root node at least one of theshortest or most direct path between such source node and suchdestination node using such tree structured network; and transmitting amessage packet from such source node to such destination node utilizingsuch determined path.
 23. A method as in claim 22, wherein said meteringdevice endpoints comprise electricity metering devices with associatedwireless communications devices.
 24. (canceled)
 25. A method as in claim22, further including providing plural autonomous systems within thetree structured network, with at least one router node within eachautonomous system, and wherein said step of determining the pathincludes requesting path information from the router node nearest to arequesting source node.
 26. A method as in claim 1, wherein the at leastone path is the shortest path.
 27. A method as in claim 1, wherein theat least one path is the most direct path.
 28. A method as in claim 1,wherein the at least one path is the shortest and the most direct path.29. A method for establishing peer-to-peer communications in an advancedmetering infrastructure, comprising: providing a plurality of nodesincluding at least one full functionality node configured as a treestructured network; initiating peer-to-peer communications from a firstnode of the plurality of nodes with a second of the plurality of nodesby requesting from the at least one full functionality node a pathrouting to the second of the plurality of nodes; determining at the atleast one full functionality node at least one of the shortest and mostdirect path between the first node and the second node; and transmittinga message packet from the first node to the second node using thedetermined path.
 30. A method for establishing peer-to-peercommunications in an advanced metering infrastructure, comprising:providing a plurality of nodes including at least one full functionalitynode and a plurality of reduced functionality nodes, configured as atree structured network; initiating peer-to-peer communications from afirst node of the plurality of reduced functionality nodes with a secondnode of the plurality of reduced functionality nodes by requesting fromthe at least one full functionality nodes a path routing to the secondnode; determining at the at least one full functionality node at leastone of the shortest or most direct path between the first node and thesecond nodes; and transmitting a message packet from the first node tothe second node using the determined path.